Improvement in paper-pulp screens



W. BLIZZARD & E. MATHER.

PAPER PULP SCREEN.

Patented June 19, 1 877.

N PE\'ER$. PHDTO-UTHOGRAPHEH, WASHINGTON. D O

UNITED STATES PATENT OFFICE;

IMPROVEMENT IN PAPER-PULP SCREENS.

Specification forming part of Letters Patent No. 192, [07,

dated June 19,1877 application filed January 20, 1877.

To all whomt't may concern:

Be it known that we, WILLIAM BLIZZARD and EDMUND MATHER, both of thecity of Harrisburg, cou'nty of Dauphin and Stateof Pennsylvania,haveinvented certain Improve! ments 'in Paper-Pulp ,Dressers, Screens,or Strainers, of which the following is a full, clear, and accuratedescription, reference being had to the accompanying drawings. making apart of this specification, in which Figure 1 represents a longitudinalsectional view of our improved apparatus, showing the screen-vat, thescreen or pulp-dresser proper, vertically bisected, and showing thestandards on the bridge-tree in vertical section at points where theymake connection with the screenattaching arms. Fig. 2 represents atransverse section made by a vertical plane through the middle of stand,screen-stem and its actuating-gear'and the regulator. Fig. 3 representsa top view of thevapparatus, showing the bridge-tree arrangedlongitudinally.

Thenovel and useful features of our improved paper-pulp dresser orstrainer consist, mainly, as follows: First, in so mounting the screenor dresser proper, by means of a central stem arranged vertically underit, that the operating mechanism acts to give it an equally-distributedvertical motion over its whole area, and independently of the screenvat;second, in providing the stem of the pulp-dresser proper with aregulator or variable stop, to regulate its motion, by means of amovable wedge operated by screw or other equivalent device; third, inproviding the body of the pulp-dresser stem with a downward extension orpin, to act in a suitable guideway at or near the foot of the gearstand,to assist in steadying the vertical motion of the said stem; fourth, incombination with said guided stem, a set of guides acting to steady thebridge-tree on which the screen is mounted, to secure the equablevertical motion thereof, already described; fifth, the device of saidbridge-tree, in combination with the screen and the aforesaid stem,arranged under the screen-vat, and actuated from a centrally-locatedactuating mechanism in the gear-stand. a

In order to show the attitude of our improvements in relation to otherdevices in the same class, it may be remarked that, in the present stateof the art to which our invention relates, several objections existagainst the present mode of mounting and operating the paper-pulpscreens, among which may be no-i ticed the following:

Said screens are usually connected at two or more points, in a dependentmanner, to the pulp through the strainers, this interference beingcaused indirectly by the spring-action or buckling of the vat-bottomsthrough said vibration.

Moreover, this vibratorymotion soon impairs the vat-structures, andnecessitates frequent and expensive repairs.

The present mode of motion is theoscillating movement, which isobjectionable for the reason that different parts of the screens areunequally agitated, and the stroke or thud given the same is lesspositive than desired.

The lost motion caused by the wear of the centers of motion, and theimperfect, regulators now usedto govern the motion, are alsoobjectionable features.

These and other objections our improvements are designed to overcome, inmanner hereinafter fully set forth and described.

In the accompanyingdrawings, Areprescnts the pulp-dresser proper orscreen, constructed in the usual manner, except that it is provided withseveral-way irons a a, each having an arm, S, as shown, for theattachment of the screen to the standards 0, made in inverted arch orbranch-stay form, and adapted to be bolted on the ends W of thebridge-tree W, in position as shown, said bridge-tree being locatedhorizontally under the middle of the screen-vat B. Said bridge-tree W ismounted at its middle on the stem P L, which is a vertical plunger,operating by reciprocatory rectilinear motion between the walls K K ofthe gear-stand, in which is mounted the horizontal driving-shaft G, onwhich is rigidly mounted the tappet-wheel O, by which the stop 0 in theeye D in said stem P L is tripped to produce the vertical motion for thescreen A. The lower end of said stem 1? L is provided with the extensionR, which is guided in a way, n, in the base L L of the gear-stand K K,to assist in giving a steady vertical motion to the stem P L when atwork.v Said stem P L is directed at its upper end by the bridge-tree W,to which it is rigidly attached, and said bridge-tree is guided andaligned by the standards E E, in the .tops of which it is confined inslots, and thus guarded against lateral motion. Said standards E E arefastened to firm foundations at bases, independent of the vat structure,that the latter may be undisturbed by the screen while in operation.

The screen Abeing guided as already stated, the motion given to it iscommunicated to it as near as possible in the vertical line of itscenter of gravity by the tappet-wheel G engaging with its step-teeth thestep-tooth G in the stem P L, said tappet-wheel being driven by shaftGin the usual manner, thus causing a reciprocatory vertical movement forthe screen A.

Said movement is regulated or suspended at the will of the operator bymeans of an adjustable wedge, M, manipulated by the nut Q T, said wedgebeing interposed between a square offset on the stem? L and the base L Lof the gear stand K K insuch manner that the return stroke of thestem PL is stopped on said wedge, thus giving blows to the screen i A, andsaid blows are modified by the position of said wedge M. If said wedgeis passed fully into the gear-stand the tappet action is entirelysuspended, and it is made more active the further the wedge isretracted, its movements and place being determined by the flanged nut QT acting in the standard m, as shown in Fig. 2.

Several very decided advantages are obtained by our improvements, amongwhich may be noticed, first, a firm blow is given and distributedequally over all parts of the screenplates; second, an efficientregulator for the screen-motion is provided; third, an independentscreen-motion, leaving the vat-structure completely intact, thusinsuring its life and avoiding the damaging results above referred to;fourth, a much higher degree of efl'ectiveness in the screen-operationby the employment of rectilinear instead of oscillatory motion.

Having thus fully and clearly described our invention, what we regard asnew and useful, and what we desire to secure by Letters Patent of theUnited States, is embraced in the following claims:

1. A paper-pulp screen mounted upon a central stem as its sole support,and guided as described, whereby an equal vertical motion is imparted toall its parts by the operating mechanism, substantially as set forth.

' 2. The paper-pulp screen A, provided with the screen-supporting stem PL, located centrally thereunder, and guided as described, in combinationwith the tappetgear O G and wedge M, regulated by screw V and nut Q, alloperating jointly, substantially as and for the purpose set forth.

3. The paper-pulp screen A, provided with standards O,-bridge-treeW,central stem 1? L R, in combination with guides E E, stand K, tappet-gar O G, and wedgeM and its ad- Justin g devices V Q m all arranged andoperating substantially as and for the purpose set forth,

WILLIAM BLIZZARD. EDMUND MATHER.

Witnesses THEOPHILUS WEAVER, PETER STUGKER.

